Method and apparatus for detecting a non-operational status of a catalyst in an engine exhaust conduit
AssigneeDelphi Technologies, Inc.
InventorRonald E. Gaskins
Life of this patent
Estimating the term…
Abstract
A quantity of unburned fuel is provided through a combustion chamber of an engine and an exhaust conduit to a catalytic converter. The catalyst in the converter is determined to be non-operational if a post-catalyst temperature sensor does not indicate a sufficient temperature increase between readings before and after provision of the unburned fuel to the combustion chamber. The unburned fuel may be provided by withholding spark ignition to create a misfire in the combustion chamber or, particularly in a direct injection engine, by injecting the fuel during the exhaust stroke.
Claims12
A method of sensing and signalling a non-operational status of a catalyst in a catalytic converter in an exhaust conduit of a combustion engine, the engine having a fuel charge supply apparatus providing a fuel charge to combustion chambers of the engine with a predetermined air/fuel ratio in response to a pre-catalyst oxygen sensor in the exhaust conduit, the method comprising the steps:
- providing a post-catalyst temperature sensor in the exhaust conduit;
- reading the post-catalyst temperature sensor to provide an initial sampled exhaust gas temperature;
- providing a quantity of unburned fuel through at least one of the combustion chambers to the catalytic converter during an idle period of engine operation while temporarily suspending a response of the fuel charge apparatus to the pre-catalyst oxygen sensor;
- monitoring the post-catalyst temperature sensor at a predetermined propagation delay time after providing the quantity of unburned fuel to provide an additional sampled exhaust gas temperature;
- comparing a temperature difference between the additional sampled exhaust gas temperature and the initial sampled exhaust gas temperature with a predetermined reference value;
- and
- signalling a non-operational status of the catalyst if the temperature difference does not exceed the predetermined reference value.
A catalyst operational state monitoring system for use with a combustion engine having an exhaust conduit with a catalytic converter and further having a fuel charge supply apparatus providing a fuel charge to the combustion chambers with a predetermined air/fuel ratio in response to a pre-catalyst oxygen sensor in the exhaust conduit, the monitoring system comprising:
- a post-catalyst temperature sensor in the exhaust conduit;
- and
- a digital processor adapted to:
- read the post-catalyst temperature sensor to provide an initial sampled exhaust gas temperature,
- provide a quantity of unburned fuel through at least one of the combustion chambers to the catalytic converter during an idle period of engine operation while temporarily suspending a response of the fuel charge apparatus to the pre-catalyst oxygen sensor,
- monitor the post-catalyst temperature sensor at a predetermined time after providing the quantity of unburned fuel to provide an additional sampled exhaust gas temperature,
- compare a temperature difference between the additional sampled exhaust gas temperatures and the initial sampled exhaust gas temperature with a predetermined reference value, and
- signal a non-operational status of the catalyst if the temperature difference does not exceed the predetermined reference value.
Dependencies are inferred from the claim text.